Outcome after intrapartum asphyxia in term infants

Animal models for neonatal brain injury induced by hypoxic ischemic conditions in rodents

Neonatal hypoxia-ischemia and resulting encephalopathies are of significant concern. Intrapartum asphyxia is a leading cause of neonatal death globally. Among surviving infants, there remains a high incidence of hypoxic-ischemic encephalopathy due to neonatal hypoxic-ischemic brain injury, manifesting as mild conditions including attention deficit hyperactivity disorder, and debilitating disorders such as cerebral palsy. Various animal models of neonatal hypoxic brain injury have been implemented to explore cellular and molecular mechanisms, assess the potential of novel therapeutic strategies, and characterize the functional and behavioural correlates of injury. Each of the animal models has individual advantages and limitations. The present review looks at several widely-used and alternative rodent models of neonatal hypoxia and hypoxia-ischemia; it highlights their strengths and limitations, and their potential for continued and improved use.

Umbilical artery pH and base excess at birth are poor predictors of neurodevelopmental morbidity in early childhood

AIM

We sought to evaluate the associations between umbilical artery pH and base excess and neurodevelopmental outcome at four years of age.

METHODS

This study comprised 84 588 singleton children born alive at term in 2005-2011 in the hospital district of Helsinki and Uusimaa in Finland. Data from the maternity hospital information system were linked to the data from the Medical Birth Register and the Hospital Discharge Register. Neurodevelopmental morbidity included cerebral palsy, epilepsy, intellectual or sensorineural impairment.

RESULTS

After adjustment for maternal and perinatal factors, a combination of pH <7.00 and base excess <-16.00 was associated with infant death (adjusted odds ratio 19.97; 95% confidence interval 5.38-74.17). Values of pH 7.00-7.10 were associated with cerebral palsy (adjusted odds ratio 2.40; 95% confidence interval 1.05-5.47). A combination of low five-minute Apgar score and umbilical artery base excess <-16.00 showed the highest positive predictive value (9.1%) for neurodevelopmental impairments. When umbilical artery pH <7.00 was included, a positive predictive value of 25.0% was observed for infant mortality.

CONCLUSION

Low umbilical artery pH and base excess at birth were the poor predictors of long-term neurodevelopmental morbidity in an unselected population. However, these parameters might be useful in assessing the risk of infant mortality.

The Investigation of Rate of Birth Asphyxia and its Relationship with Delivery Mode at Shahid Beheshti Hospital of Isfahan during 2013, 2014, and 2015

BACKGROUND

Birth asphyxia is considered as one of the biggest challenges faced by perinatal care experts. According to the WHO, in 2005, one-fourth of infant mortality cases occurred due to birth asphyxia.

METHODS

This study is a retrospective study done on the newborn population with gestational ages of 36 weeks or higher during the years 2013, 2014, and 2015 to find the relationship between the number of birth asphyxia cases and the years. As a secondary objective, the relationship between the mode of delivery and the cases of birth asphyxia were investigated using logistic regression test. The inclusion criteria consisted of three cases, namely, gestational age of 36 weeks or higher, 5 min Apgar of <5, and umbilical cord pH of <7.1. The exclusion criteria involved hydrops fetalis, cyanotic heart disease, chromosomal abnormality, and congenital infections.

RESULTS

From the two independent variables of the study, only the variable "year" showed a significant difference between the years 2013 and 2015 (P < 0.01). The delivery mode did not have any statistically significant influence on the newborns' affliction with birth asphyxia (P = 0.993).

CONCLUSIONS

According to the results, there is a significant difference between the rate of birth asphyxia in Iran and its global rate in 2015, and regarding its multiple growth from 2013 to 2015, conducting a more comprehensive and extensive research on birth asphyxia risk factors at a delivery time seems justified and inevitable.

MR Imaging of hypoxic ischemic encephalopathy - Distribution Patterns and ADC value correlations

Background and purpose

Neonatal hypoxic-ischemic encephalopathy causes hypoxic brain injury. Due to differences in brain maturity at time of insult, severity of hypotension and duration of insult, there are four distinct patterns of brain injury. Magnetic resonance imaging is the most sensitive modality for evaluating these patterns of brain injury. Additional role of Diffusion weighted imaging and ADC values can be useful in the evaluation of such cases. We conducted this study to analyse the usefulness of ADC values in the brain tissue affected by hypoxic-ischemic injury.

Materials and Methods

We conducted a prospective study of all the patients referred to our department for magnetic resonance scanning of brain with history of hypoxic ischemic encephalopathy and clinical features cerebral palsy. 23 Cases with imaging manifestations of hypoxic ischemic encephalopathy were included in the study. We studied distribution patterns of HIE in our cases and calculated the ADC values of involved as well as normal grey and white matter. Further, sensitivity, specificity, predictive values, and likelihood ratios for each dichotomized diffusion and ADC values were obtained Wilson Score method.

Results

The most common distribution pattern in our study was involvement of peri-rolandic area (15 cases, 65%). ADC values were significantly (p < 0.005) increased in abnormal white matter. No significant changes (p = 0.8) were seen in ADC values of normal and abnormal grey matter.

Conclusions

Due to significant increase in ADC values of affected white matter, ADC value can be used as a marker to detect chronic sequel of hypoxic ischaemic brain injury. Another observation was the perirolandic brain tissue being most common area of involvement in the cases with cerebral palsy.

Effect of hypoxia on the retina and superior colliculus of neonatal pigs

Purpose

To evaluate the effect of hypoxia on the neonatal pig retina and brain, we analysed the retinal ganglion cells (RGCs) and neurons in the superior colliculus, as well as the response of astrocytes in both these central nervous system (CNS) structures.

Methods

Newborn pigs were exposed to 120 minutes of hypoxia, induced by decreasing the inspiratory oxygen fraction (FiO₂: 10–15%), followed by a reoxygenation period of 240 minutes (FiO₂: 21–35%). RGCs were quantified using Brn3a, a specific nuclear marker for these cells, and apoptosis was assessed through the appearance of active caspase-3. A morphometric analysis of the cytoskeleton of astrocytes (identified with GFAP) was performed in both the retina and superior colliculus.

Results

Hypoxia produced no significant change in the RGCs, although, it did induce a 37.63% increase in the number of active caspase-3 positive cells in the superior colliculus. This increase was particularly evident in the superficial layers of the superior colliculus, where 56.93% of the cells were positive for active caspase-3. In addition, hypoxia induced changes in the morphology of the astrocytes in the superior colliculus but not in the retina.

Conclusions

Hypoxia in the neonatal pig does not affect the retina but it does affect more central structures in the brain, increasing the number of apoptotic cells in the superior colliculus and inducing changes in astrocyte morphology. This distinct sensibility to hypoxia may pave the way to design specific approaches to combat the effects of hypoxia in specific areas of the CNS.

Aquaporin-4 knockdown ameliorates hypoxic-ischemic cerebral edema in newborn piglets

Emerging evidence indicates that the water channel protein aquaporin 4 (AQP4) plays an essential role in water homeostasis and is implicated in the pathogenesis of brain edema. This study aimed to understand the physiological role of AQP4 in hypoxia-ischemia-mediated cytotoxic brain edema. We specifically knocked down AQP4 expression by intracerebral injection of a plasmid containing AQP4 siRNA into a neonatal piglet model. The success of the hypoxia-ischemia-induced piglet model was confirmed by conventional magnetic resonance imaging and diffusion-weighted imaging. AQP4 knockdown led to reduced brain edema accompanied by a higher apparent diffusion coefficient value, compared to the control group injected with a plasmid containing scrambled siRNA. Real-time polymerase chain reaction and immunohistochemical analysis confirmed that AQP4 siRNA significantly reduced AQP4 mRNA and protein expression. Finally, neurological function analysis revealed that AQP4 knockdown significantly improved neurobehavioral manifestation of the piglets after exposure to hypoxia-ischemia. Taken together, these results indicate that AQP4 plays an important role in mediating brain edema in hypoxic-ischemic encephalopathy. Therefore, AQP4 could be a therapeutic target to ameliorate early-stage brain edema.

Neuroprotective therapies after perinatal hypoxic-ischemic brain injury

Hypoxic-ischemic (HI) brain injury is one of the main causes of disabilities in term-born infants. It is the result of a deprivation of oxygen and glucose in the neural tissue. As one of the most important causes of brain damage in the newborn period, the neonatal HI event is a devastating condition that can lead to long-term neurological deficits or even death. The pattern of this injury occurs in two phases, the first one is a primary energy failure related to the HI event and the second phase is an energy failure that takes place some hours later. Injuries that occur in response to these events are often manifested as severe cognitive and motor disturbances over time. Due to difficulties regarding the early diagnosis and treatment of HI injury, there is an increasing need to find effective therapies as new opportunities for the reduction of brain damage and its long term effects. Some of these therapies are focused on prevention of the production of reactive oxygen species, anti-inflammatory effects, anti-apoptotic interventions and in a later stage, the stimulation of neurotrophic properties in the neonatal brain which could be targeted to promote neuronal and oligodendrocyte regeneration.

Morphological evaluation of the cerebral blood vessels in the late gestation fetal sheep following hypoxia in utero

Hypoxia can significantly contribute to the development of permanent brain injury in the term neonate; however the response of cerebral blood vessels is not well understood. This study aimed to quantitatively measure vascular density and morphology using laminin immunohistochemistry as a marker of blood vessels, and determine the effects of a single, severe bout of hypoxia (umbilical cord occlusion, UCO) late in gestation on the developing cerebrovasculature in fetal sheep. At 124-126 days gestation singleton fetal sheep underwent surgery for implantation of catheters and placement of an inflatable cuff around the umbilical cord. A 10 min UCO or sham UCO (n=5) occurred at 132 days gestation. Fetal brains were collected at 24 h (n=5) or 48 h (n=4) after UCO for vascular density and morphology analysis of laminin immunohistochemistry. 48 h following a single, brief bout of severe hypoxia late in gestation decreased vascular density was seen in the caudate nucleus and no changes in vascular morphology occurred. However closer analysis revealed a significant shift in the frequency of smaller (≤10 μm) to larger (≤100 μm) perimeter blood vessels in periventricular and subcortical white matter. Close examination of the frequency distribution of vascular perimeter highlights that alterations in vascular morphology persist in the near term fetal brain for up to 48 h following a brief (10 min) hypoxia in white but not gray matter. These findings suggest that the near term brain may still be vulnerable to white matter injury following in utero hypoxia.

Pilot randomized trial of therapeutic hypothermia with serial cranial ultrasound and 18-22 month follow-up for neonatal encephalopathy in a low resource hospital setting in Uganda: study protocol

Background

There is now convincing evidence that in industrialized countries therapeutic hypothermia for perinatal asphyxial encephalopathy increases survival with normal neurological function. However, the greatest burden of perinatal asphyxia falls in low and mid-resource settings where it is unclear whether therapeutic hypothermia is safe and effective.

Aims

Under the UCL Uganda Women's Health Initiative, a pilot randomized controlled trial in infants with perinatal asphyxia was set up in the special care baby unit in Mulago Hospital, a large public hospital with ~20,000 births in Kampala, Uganda to determine:

(i) The feasibility of achieving consent, neurological assessment, randomization and whole body cooling to a core temperature 33-34°C using water bottles

(ii) The temperature profile of encephalopathic infants with standard care

(iii) The pattern, severity and evolution of brain tissue injury as seen on cranial ultrasound and relation with outcome

(iv) The feasibility of neurodevelopmental follow-up at 18-22 months of age

Methods/Design

Ethical approval was obtained from Makerere University and Mulago Hospital. All infants were in-born. Parental consent for entry into the trial was obtained. Thirty-six infants were randomized either to standard care plus cooling (target rectal temperature of 33-34°C for 72 hrs, started within 3 h of birth) or standard care alone. All other aspects of management were the same. Cooling was performed using water bottles filled with tepid tap water (25°C). Rectal, axillary, ambient and surface water bottle temperatures were monitored continuously for the first 80 h. Encephalopathy scoring was performed on days 1-4, a structured, scorable neurological examination and head circumference were performed on days 7 and 17. Cranial ultrasound was performed on days 1, 3 and 7 and scored. Griffiths developmental quotient, head circumference, neurological examination and assessment of gross motor function were obtained at 18-22 months.

Discussion

We will highlight differences in neonatal care and infrastructure that need to be taken into account when considering a large safety and efficacy RCT of therapeutic hypothermia in low and mid resource settings in the future.

Trial registration

Current controlled trials ISRCTN92213707

Serial MRI and neurodevelopmental outcome in 9- to 10-year-old children with neonatal encephalopathy

OBJECTIVE

To assess the relation between patterns of brain injury on neonatal and childhood magnetic resonance imaging (MRI) and long-term neurodevelopmental outcome.

STUDY DESIGN

Neonatal (n = 34) and childhood MRIs (n = 77) were analyzed for 80 children with neonatal encephalopathy and for 51 control subjects during childhood. MRIs were graded as normal, mildly abnormal (white matter lesions), or moderately/severely abnormal (watershed injury, lesions in basal ganglia/thalamus or focal infarction). Severity of brain injury was related to different aspects of neurologic outcome: Total impairment score of the Movement Assessment Battery for Children, intelligence quotient score, cerebral palsy, postneonatal epilepsy, and need for special education. Seven children with neonatal encephalopathy required extracorporeal membrane oxygenation treatment.

RESULTS

Neonatal and childhood MRI were comparable in 25/33 children (75.8%, P < .001). Children with moderate/severe lesions on neonatal or childhood MRI more often had a total impairment score <or= 15th percentile, an intelligence quotient <or= 85, and cerebral palsy, and attended special education.

CONCLUSION

Different patterns of injury seen on neonatal MRI after neonatal encephalopathy can still be recognized on childhood MRI. Children with moderate to severe brain lesions on neonatal or childhood MRI significantly more often have impaired motor and cognitive outcomes.

Term intra-partum asphyxia: an analysis of acute non-specific supportive criteria and non-CNS organ injury

OBJECTIVE

The purpose of this study was to describe the frequencies and relationships of non-specific non-essential diagnostic criteria and non-CNS organ system injury in term intra-partum asphyxia.

METHODS

All children with term intra-partum asphyxia encountered in a single pediatric neurology practice with at least two years follow-up and an abnormal neurologic outcome were identified.

RESULTS

A total of 40 children (28 males, 12 females) were identified. Twenty-four had moderate NE and sixteen severe NE. The mean number of non-specific non-essential diagnostic criteria (out of a possible 7) was 4.75+/-1.39 SD. Sixty percent had five or more criteria and all criteria were present in only 10% of newborns. The mean number of non-CNS organ systems affected was 2.88+/-1.96 SD (out of a possible 6). Ten percent of our sample showed no evident non-CNS organ injury acutely.

CONCLUSION

Most asphyxiated neonates failed to consistently satisfy all elements of present consensus statements.

Experimental treatments for hypoxic ischaemic encephalopathy

Hypoxic ischaemic encephalopathy continues to be a significant cause of death and disability worldwide. In the last 1-2 years, therapeutic hypothermia has entered clinical practice in industrialized countries and neuroprotection of the newborn has become a reality. The benefits and safety of cooling under intensive care settings have been shown consistently in trials; therapeutic hypothermia reduces death and neurological impairment at 18 months with a number needed to treat of approximately nine. Unfortunately, around half the infants who receive therapeutic hypothermia still have abnormal outcomes. Recent experimental data suggest that the addition of another agent to cooling may enhance overall protection either additively or synergistically. This review discusses agents such as inhaled xenon, N-acetylcysteine, melatonin, erythropoietin and anticonvulsants. The role of biomarkers to speed up clinical translation is discussed, in particular, the use of the cerebral magnetic resonance spectroscopy lactate/N-acetyl aspartate peak area ratios to provide early prognostic information. Finally, potential future therapies such as regeneration/repair and postconditioning are discussed.

Obstetric aspects of hypoxic ischemic encephalopathy

Hypoxic ischemic encephalopathy (HIE) describes neonatal encephalopathy that is caused by intrapartum asphyxia and it can result in the long term sequelae of cerebral palsy which is a major cause of disability. The incidence of cerebral palsy has not changed over the last few decades and the challenge to obstetricians remains how best to recognise those babies at risk of this intrapartum insult both before and during labour. Many associations and risk factors are unavoidable or unrecognisable, and others are fairly common and associated with poor predictive value. Intrapartum fetal heart monitoring remains the main focus of attention but how this is best achieved is still the subject of research. Computerised decision support systems built into fetal heart rate monitoring and non-invasive fetal ECG signal pick-up are currently being explored.

Neonatal ECMO Study of Temperature (NEST)--a randomised controlled trial

BACKGROUND

Existing evidence indicates that once mature neonates with severe cardio-respiratory failure become eligible for Extra Corporeal Membrane Oxygenation (ECMO) their chances of intact survival are doubled if they actually receive ECMO. However, significant numbers survive with disability. NEST is a multi-centre randomised controlled trial designed to test whether, in neonates requiring ECMO, cooling to 34 degrees C for the first 48 to 72 hours of their ECMO course leads to improved later health status. Infants allocated to the control group will receive ECMO at 37 degrees C throughout their course, which is currently standard practice around the world. Health status of both groups will be assessed formally at 2 years corrected age.

METHODS/DESIGN

All infants recruited to the study will be cared for in one of the four United Kingdom (UK) ECMO centres. Babies who are thought to be eligible will be assessed by the treating clinician who will confirm eligibility, ensure that consent has been obtained and then randomise the baby using a web based system, based at the National Perinatal Epidemiology Unit (NPEU) Clinical Trials Unit. Trial registration.Babies allocated ECMO without cooling will receive ECMO at 37 degrees C +/- 0.2 degrees C. Babies allocated ECMO with cooling will be managed at 34 degrees C +/- 0.2 degrees C for up to 72 hours from the start of their ECMO run. The minimum duration of cooling will be 48 hours. Rewarming (to 37 degrees C) will occur at a rate of no more than 0.5 degrees C per hour. All other aspects of ECMO management will be identical.

PRIMARY OUTCOME

Cognitive score from the Bayley Scales of Infant and Toddler Development, 3rd edition (Bayley-III) at age of 2 years (24 - 27 months).

DISCUSSION

For the primary analysis, children will be analysed in the groups to which they are assigned, comparing the outcome of all babies allocated to "ECMO with cooling" with all those allocated to "ECMO" alone, regardless of deviation from the protocol or treatment received. For the primary outcome the analysis will compare the mean scores for each group of surviving babies. The rationale for this choice of primary analysis is to give a fair representation of the average ability of assessable children, accepting the limitation that excluding deaths might impose.The consistency of the effect of cooling on the group of babies recruited to the trial will be explored to see whether cooling is of particular help, or not, to specific subgroups of infants, using the statistical test of interaction. Therefore pre-specified subgroup analyses include: (i) whether the ECMO is veno-arterial or veno-venous; (ii) whether the child's oxygenation index at the time of recruitment is <60 or > or = 60; (iii) initial aEEG pattern shown on the cerebral function monitor, and (iv) primary diagnostic group.

TRIAL REGISTRATION

Current Controlled Trials ISRCTN72635512.

The spectrum of abnormal neurologic outcomes subsequent to term intrapartum asphyxia

The purpose of this study was to describe the spectrum of possible abnormal neurologic outcomes in term infants with intrapartum asphyxia and to identify those clinical factors associated with the later occurrence of cerebral palsy. All children with term intrapartum asphyxia encountered in a single pediatric neurologic practice with at least 2 years of follow-up and an abnormal neurologic outcome were identified. Abnormal outcomes were grouped into those with or without cerebral palsy. A total of 40 children (28 male, 12 female) met study criteria. Of these, 23 developed cerebral palsy; the remaining 17 children developed an abnormal neurologic outcome that did not include cerebral palsy. A more severe grade of neonatal encephalopathy, a higher number of neonatal seizures, the neonatal use of phenytoin, diffuse abnormalities on imaging, and abnormal findings on neurologic examination at neonatal discharge were all significantly (P<0.05) associated with an abnormal outcome that included cerebral palsy. Abnormal neurologic outcomes other than cerebral palsy subsequent to term intrapartum asphyxia may occur. It appears that a more severe grade of apparent initial clinical injury is more likely to result in an outcome featuring cerebral palsy.

Do apparent diffusion coefficient measurements predict outcome in children with neonatal hypoxic-ischemic encephalopathy?

BACKGROUND AND PURPOSE

Diffusion-weighted imaging (DWI) permits early detection and quantification of hypoxic-ischemic (HI) brain lesions. Our aim was to assess the predictive value of DWI and apparent diffusion coefficient (ADC) measurements for outcome in children with perinatal asphyxia.

MATERIALS AND METHODS

Term neonates underwent MR imaging within 10 days after birth because of asphyxia. MR imaging examinations were retrospectively evaluated for HI brain damage. ADC was measured in 30 standardized brain regions and in visibly abnormal areas on DWI. In survivors, developmental outcome until early school age was graded into the following categories: 1) normal, 2) mildly abnormal, and 3) definitely abnormal. For analysis, category 3 and death (category 4) were labeled "adverse," 1 and 2 were "favorable," and 2-3 and death were "abnormal" outcome. Differences in outcome between infants with and without DWI abnormalities were analyzed by using chi(2) tests. The nonparametric Mann-Whitney U test analyzed whether ADC values in visible DWI abnormalities correlated with age at imaging. Logistic regression analysis tested the predictive value for outcome of the ADC in each standardized brain region. Receiver operating characteristic analysis was used to find optimal ADC cutoff values for each region for the various outcome scores.

RESULTS

Twenty-four infants (13 male) were included. Mean age at MR imaging was 4.3 days (range, 1-9 days). Seven infants died. There was no difference in outcome between infants with and without visible DWI abnormalities. Only ADC of the posterior limb of the internal capsule correlated with age. ADC in visibly abnormal DWI regions did not have a predictive value for outcome. Of all measurements performed, only the ADC in the normal-appearing basal ganglia and brain stem correlated significantly with outcome; low ADC values were associated with abnormal/adverse outcome, and higher ADC values, with normal/favorable outcome (basal ganglia: P = .03 for abnormal, P = .01 for adverse outcome; brain stem: P = .006 for abnormal, P = .03 for adverse outcome).

CONCLUSIONS

ADC values in normal-appearing basal ganglia and brain stem correlated with outcome, independently of all MR imaging findings including those of DWI. ADC values in visibly abnormal brain tissue on DWI did not show a predictive value for outcome.

Is there a way to predict outcome in (near) term neonates with hypoxic-ischemic encephalopathy based on MR imaging?

BACKGROUND AND PURPOSE

It has previously been demonstrated that comparison of signal intensity (SI) between selected brain structures on T1-weighted images enables distinction between the absence or presence of hypoxic-ischemic (HI) brain injury in young infants. The aim of the present study was to assess whether this method of brain structure T1-weighted SI comparison also enables prediction of outcome.

MATERIALS AND METHODS

Survivors of a group of 57 children with neonatal HI encephalopathy (HIE) grade 2 or 3 according to Sarnat and Sarnat and controls who underwent neonatal MR imaging were retrospectively assigned to 1 of 3 outcome groups at 5 years of age, depending on developmental outcome: 1) normal, 2) mildly abnormal, and 3) definitely abnormal. Gestational age was not significantly different between the HIE group (range, 35 + 5-42 + 5 weeks; mean, 39 + 4 weeks) and control group (range, 35 + 0-42 + 1 weeks; mean, 39 + 2 weeks). We calculated the predictive values of the neonatal clinical HIE classification according to Sarnat and Sarnat for outcome (neonatal death and developmental outcome in survivors). We assessed which brain structure T1-weighted SI comparison scored best for outcome prediction. Predictive values of that comparison for outcome were calculated for the entire group and for the HIE grade 2 group only, a patient group with highly variable outcome.

RESULTS

Of the 57 children, 6 died. Outcome group 1 consisted of 31; group 2, of 14; and group 3, of 6 children. The positive predictive value of the neonatal clinical classification for adverse outcome (outcome group 3 and death) was 52%; and negative predictive value, 100%. These were respectively 45% and 0% in children with HIE grade 2. Of all brain structure T1-weighted SI comparisons, that of the posterior limb of the internal capsule versus the posterolateral putamen scored best for outcome prediction. The positive predictive value for adverse outcome was 69%; and negative predictive value, 98%. In children with HIE grade 2, the positive predictive value and negative predictive value for adverse outcome were 67% and 88%.

CONCLUSIONS

Brain structure T1-weighted SI comparisons are helpful to predict outcome in (near) term neonates with HIE. This finding adds to the current knowledge and clinical practice. If the SI in the posterolateral putamen is less than the SI in the posterior limb of the internal capsule, favorable outcome is very likely, whereas if the SI in the posterolateral putamen is equal to or greater than the SI in the posterior limb of the internal capsule, adverse outcome is very likely. In neonates with HIE grade 2 according to Sarnat and Sarnat, prediction of outcome is substantially improved by using these brain structure T1-weighted SI comparisons.

[Relation between the resistance index obtained by the transfontanellar Doppler ultrasonography and the neurological development until the first year of life in term infants with mild or moderate hypoxic-ischaemic encephalopathy]

OBJECTIVE

To evaluate the relation between the resistance index (RI) obtained by transfontanellar Doppler ultrasonography, and the neurodevelopment until one year of life, at term newborns with mild or moderate hypoxic-ischaemic encephalopathy due to intrapartum asphyxia.

METHOD

20 term newborns, with mild or moderate hypoxic-ischemic encephalopathy, high values of resistance index in the first exam, and without cerebral morfologic abnormalities or other diseases. They were submitted to serial bimonthly transfontanellar Doppler ultrasonography, from the seventh day of life on, and monthly clinical neurodevelopment assessment until one year of life.

RESULTS

There was a progressive normalization of RI values until the last examination. In five cases there were clinical neurologic normalization in the neonatal period after the first Doppler exam. Fifteen infants presented neurologic abnormalities, with normalization after the second trimester of life.

CONCLUSION

There was a relation between the normal RI values with the normalization of the clinical assessment.

Outcome after intrapartum hypoxic ischaemia at term

We consider the range of childhood disabilities that have been attributed to perinatal hypoxic ischaemia at term and review the strength of evidence for each. The strongest evidence is for a causal link between acute profound hypoxic ischaemia and dyskinetic tetraplegic cerebral palsy (CP). Hemiplegic CP is not usually due to a perinatal hypoxic ischaemic insult at term; an important cause is focal cerebral infarction or 'stroke'. Characteristically, diplegic CP is seen in ex-preterm children with periventricular leukomalacia. Ataxic CP is unlikely to be due to perinatal asphyxia. Recent careful follow-up studies have shown that childhood survivors of perinatal hypoxic ischaemia are at risk for cognitive deficits even in the absence of functional motor disorders. There is no evidence that, in isolation, either attention deficit hyperactivity disorder or autism is caused by hypoxic ischaemia. As effective neuroprotective therapies are introduced, notably cooling, it is possible that the prevalence of CP may be reduced.

Long-term cognitive and behavioral consequences of neonatal encephalopathy following perinatal asphyxia: a review

Neonatal encephalopathy (NE) following perinatal asphyxia (PA) is considered an important cause of later neurodevelopmental impairment in infants born at term. This review discusses long-term consequences for general cognitive functioning, educational achievement, neuropsychological functioning and behavior. In all areas reviewed, the outcome of children with mild NE is consistently positive and the outcome of children with severe NE consistently negative. However, children with moderate NE form a more heterogeneous group with respect to outcome. On average, intelligence scores are below those of children with mild NE and age-matched peers, but within the normal range. With respect to educational achievement, difficulties have been found in the domains reading, spelling and arithmetic/mathematics. So far, studies of neuropsychological functioning have yielded ambiguous results in children with moderate NE. A few studies suggest elevated rates of hyperactivity in children with moderate NE and autism in children with moderate and severe NE.

CONCLUSION

Behavioral monitoring is required for all children with NE. In addition, systematic, detailed neuropsychological examination is needed especially for children with moderate NE.

Magnetic resonance imaging of neonatal encephalopathy at 4.7 tesla: initial experiences

OBJECTIVES

The goals were to develop safe 4.7-T MRI examination protocols for newborn infants and to explore the advantages of this field strength in neonatal encephalopathy.

METHODS

Nine ventilated newborn infants with moderate or severe encephalopathy were studied at 4.7 T, with ethical approval and informed parental consent. The custom-made, 4.7-T-compatible, neonatal patient management system included acoustic noise protection and physiologic monitoring. An adult head coil was used. Acquisition parameters for T2-weighted fast spin echo MRI and a variety of T1-weighted methods were adapted for MRI of neonatal brain at 4.7 T. The pulse sequences used had a radiofrequency specific absorption rate of <2 W/kg.

RESULTS

Physiologic measures were normal throughout each scan. T2-weighted fast spin echo imaging provided better anatomic resolution and gray/white matter contrast than typically obtained at 1.5 T; T1-weighted images were less impressive.

CONCLUSIONS

With appropriate safety precautions, MRI of newborn infants undergoing intensive care is as feasible at 4.7 T as it is at 1.5 T; our initial studies produced T2-weighted fast spin echo images with more detail than commonly obtained at 1.5 T. Although T1-weighted images were not adequately informative, additional pulse sequence optimization may be advantageous. A smaller neonatal head coil should also permit greater flexibility in acquisition parameters and even more anatomic resolution and tissue contrast. In neonatal encephalopathy, interpretation of the T2-weighted pathologic detail in combination with comprehensive neurodevelopmental follow-up should improve prognostic accuracy and enable more patient-specific therapeutic interventions. In addition, more precise relationships between structural changes and functional impairment may be defined.

Does perinatal asphyxia impair cognitive function without cerebral palsy?

Some studies on neurodevelopmental outcomes after neonatal encephalopathy have suggested that cognitive deficits do not occur in the absence of cerebral palsy. It is increasingly apparent that childhood survivors of overt neonatal encephalopathy may have cognitive impairments, even in the absence of functional motor deficits. The risk of cognitive deficits is related to the severity of neonatal encephalopathy and the pattern of brain injury on neuroimaging, particularly the watershed pattern of injury. A better understanding of the risk factors for cognitive abnormalities after neonatal encephalopathy will ultimately lead to interventions to prevent these deficits. Identifying the full spectrum of neurodevelopmental outcomes after neonatal encephalopathy will also allow care givers to identify children requiring early intervention to maximise their potential for independent function throughout development.

Comparative prognostic utilities of early quantitative magnetic resonance imaging spin-spin relaxometry and proton magnetic resonance spectroscopy in neonatal encephalopathy

OBJECTIVE

We sought to compare the prognostic utilities of early MRI spin-spin relaxometry and proton magnetic resonance spectroscopy in neonatal encephalopathy.

METHODS

Twenty-one term infants with neonatal encephalopathy were studied at a mean age of 3.1 days (range: 1-5). Basal ganglia, thalamic and frontal, parietal, and occipital white matter spin-spin relaxation times were determined from images with echo times of 25 and 200 milliseconds. Metabolite ratios were determined from an 8-mL thalamic-region magnetic resonance spectroscopy voxel (1H point-resolved spectroscopy; echo time 270 milliseconds). Outcomes were assigned at age 1 year as follows: (1) normal, (2) moderate (neuromotor signs or Griffiths developmental quotient of 75-84), (3) severe (functional neuromotor deficit or developmental quotient <75 or died). Predictive efficacies for differentiation between normal and adverse (combined moderate and severe) outcomes were compared by receiver operating characteristic curve analysis and logistic regression.

RESULTS

Thalamic and basal ganglia spin-spin relaxation times correlated positively with outcome and predicted adversity. Although thalamic and basal ganglia spin-spin relaxation times were prognostic of adversity, magnetic resonance spectroscopy metabolite ratios were better predictors, and, of these, lactate/N-acetylaspartate was most accurate.

CONCLUSIONS

Deep gray matter spin-spin relaxation time was increased in the first few days after birth in infants with an adverse outcome. Proton magnetic resonance spectroscopy was more prognostic than spin-spin relaxation time, with lactate/N-acetylaspartate the best measure. Nevertheless, both techniques were useful for early prognosis, and the potential superior spatial resolution of spin-spin relaxometry may define better the precise anatomic pattern of injury in the early days after birth.

Brain and cognitive-behavioural development after asphyxia at term birth

Perinatal asphyxia occurs in approximately 1-6 per 1000 live full-term births. Different patterns of brain damage can result, though the relation of these patterns to long-term cognitive-behavioural outcome remains under investigation. The hippocampus is one brain region that can be damaged (typically not in isolation), and this site of damage has been implicated in two different long-term outcomes, cognitive memory impairment and the psychiatric disorder schizophrenia. Factors in addition to the acute episode of asphyxia likely contribute to these specific outcomes, making prediction difficult. Future studies that better document long-term cognitive-behavioural outcome, quantitatively identify patterns of brain injury over development and consider additional variables that may modulate the impact of asphyxia on cognitive and behavioural function will forward the goals of predicting long-term outcome and understanding the mechanisms by which it unfolds.

Infants with perinatal hypoxic ischemia: feasibility of fiber tracking at birth and 3 months

The purpose of this study was to retrospectively investigate the feasibility of fiber tracking at birth and 3 months in infants with hypoxic ischemia to detect disturbances in white matter development. This retrospective study did not require institutional review board approval. All parents gave informed consent. Diffusion-tensor magnetic resonance (MR) images were obtained in full-term newborns: seven with standard MR imaging findings and 10 with perinatal hypoxic ischemia-related abnormalities. Visualization of white matter tracts was investigated by using a volume-tracing and quantification technique. Fiber tracking was useful for studying the neonatal brain. Abnormalities resulted in fiber patterns that were different from the fiber patterns of normal brain tissue. The corona radiata fibers were frequently affected.

Demographic characteristics and clinical course in infants with moderate or severe neonatal encephalopathy

A chart review of 64 infants with moderate or severe neonatal encephalopathy showed that resuscitation was required for 61 (95%), respiratory support for 53 (83%) and anticonvulsants for 58 (91%). Death occurred in 2 (4%) infants with moderate encephalopathy and 12 (86%) with severe encephalopathy. In addition, subsequent neurodevelopment was abnormal in approximately a quarter of infants who survived after a moderate to severe encephalopathy.

Recovery of amplitude integrated electroencephalographic background patterns within 24 hours of perinatal asphyxia

OBJECTIVE

To assess the time course of recovery of severely abnormal initial amplitude integrated electroencephalographic (aEEG) patterns (flat trace (FT), continuous low voltage (CLV), or burst suppression (BS)) in full term asphyxiated neonates, in relation to other neurophysiological and neuroimaging findings and neurodevelopmental outcome.

METHODS

A total of 190 aEEGs of full term infants were reviewed. The neonates were admitted within 6 hours of birth to the neonatal intensive care unit because of perinatal asphyxia, and aEEG recording was started immediately. In all, 160 infants were included; 65 of these had an initial FT or CLV pattern and 25 an initial BS pattern. Neurodevelopmental outcome was assessed using a full neurological examination and the Griffiths' mental developmental scale.

RESULTS

In the FT/CLV group, the background pattern recovered to continuous normal voltage within 24 hours in six of the 65 infants (9%). All six infants survived the neonatal period; one had a severe disability, and five were normal at follow up. In the BS group, the background pattern improved to normal voltage in 12 of the 25 infants (48%) within 24 hours. Of these infants, one died, five survived with moderate to severe disability, two with mild disability, and four were normal. The patients who did not recover within 24 hours either died in the neonatal period or survived with a severe disability.

CONCLUSION

In this study there was a small group of infants who presented with a severely abnormal aEEG background pattern within six hours of birth, but who achieved recovery to a continuous normal background pattern within the first 24 hours. Sixty one percent of these infants survived without, or with a mild, disability.

Sleep-wake cycling on amplitude-integrated electroencephalography in term newborns with hypoxic-ischemic encephalopathy

OBJECTIVE

The objective of this amplitude-integrated electroencephalography (aEEG) study was to evaluate the influence of perinatal hypoxia-ischemia on sleep-wake cycling (SWC) in term newborns and assess whether characteristics of SWC are of predictive value for neurodevelopmental outcome.

METHODS

From a consecutive series of newborns born during a 10-year period, the aEEG tracings of 171 term newborns with hypoxic-ischemic encephalopathy were assessed for the presence, time of onset, and quality of SWC. SWC patterns were categorized with regard to the background pattern on which they presented, as normal or abnormal SWC.

RESULTS

SWC was seen in 95.4% of the surviving newborns and in 8.1% of those who died. The median time intervals from birth to onset of SWC were significantly different in newborns with hypoxic-ischemic encephalopathy grades I, II, and III (7, 33, and 62 hours, respectively). Newborns with seizure discharges developed SWC with a delay of 30.5 hours. Good outcome was associated with earlier onset of SWC and normal SWC pattern. The difference in the median Griffiths' developmental quotients in newborns who started SWC before/after 36 hours was 8.5 points. The good/poor neurodevelopmental outcome was predicted correctly by the onset of SWC before/after 36 hours in 82% of newborns.

CONCLUSIONS

The presence, time of onset, and quality of SWC reflected the severity of the hypoxic-ischemic insult to which newborns were exposed. The time of onset of SWC has a predictive value for neurodevelopmental outcome.

Diffusion-weighted magnetic resonance imaging in term perinatal brain injury: a comparison with site of lesion and time from birth

OBJECTIVE

The aim of this study was to establish a more objective method for confirming tissue injury in term neonates who present with early seizures that are believed to be hypoxic-ischemic in origin.

METHODS

We studied the relationship between contemporaneous diffusion-weighted magnetic resonance imaging and conventional magnetic resonance imaging in 63 symptomatic term-born neonates and 15 control term infants performed in the neonatal period. Apparent diffusion coefficients (ADC) were obtained for multiple regions of the brain.

RESULTS

ADC values in the 15 control infants were 1 (1-1.15) (median [range]) x 10(-3)/mm2/second in the thalami and 1.1 (1-1.3) x 10(-3)/mm2/second in the lentiform nuclei, 1.5 (1.3-1.7) x 10(-3)/mm2/second in the centrum semiovale, 1.6 (1.46-1.7) x 10(-3)/mm2/second in the anterior white matter (WM), and 1.55 (1.35-1.85) x 10(-3)/mm2/second in the posterior WM with little variation over time. ADC values were significantly reduced in the first week after severe injury to either WM or basal ganglia and thalami (BGT), but values normalized at the end of the first week and then increased during week 2. ADC values were either normal or increased in moderate BGT and WM lesions when compared with controls. ADC values < 1.1 x 10(-3)/mm2/second were always associated with WM infarction and values <0.8 x 10(-3)/mm2/second with thalamic infarction.

CONCLUSION

A reduced ADC soon after delivery allows the presence of tissue infarction to be confirmed at a time when conventional imaging changes may be subtle. However, as both moderate WM and BGT lesions may have normal or increased ADC values, a normal ADC value during the first week does not signify normal tissue. ADC values should always be measured in combination with visual analysis of both conventional and diffusion-weighed images for maximum detection of pathologic tissue, and the timing of the scan needs to be taken into account when interpreting the results.

The value of autopsy in determining the cause of failure to respond to resuscitation at birth

Autopsy is invaluable in identifying the causes of severe depression and very low Apgar score after birth and in assessing contributory conditions. Brain scans are increasingly used in the care of neonates who fail to respond to resuscitation at birth but their interpretation depends on the information gained from sound neuropathological studies. Asphyxia, both acute intrapartum asphyxia and chronic asphyxia, is an important cause of low Apgar scores. The gestational age and the nature of the asphyxial insult both have a profound influence on the ultimate pattern of injury. Asphyxia in the preterm brain tends to damage preferentially the white matter but some white matter damage is also seen in many infants who have an hypoxia-ischaemic insult at term though the predominant site of injury is to the central grey matter. The nature of the cellular damage and reactive change seen at autopsy is described. There is an association between low Apgar scores and intrauterine exposure to infection and maternal pyrexia. Detailed autopsy examination should include the search for infection. The placenta, cord and membranes should be examined in view of the mounting evidence of the association between intrauterine infection of the placenta and fetal membranes and prenatal brain damage. Additionally, the presence of placental thrombosis and infarction should be sought in relation to focal and global injury in the full term infant. Acquired prepartum lesions rarely cause the infant to present with a low Apgar score. The exception to this is severe damage to the brainstem and basal ganglia. Traumatic injury to the brain is now much less common than in previous decades. Subdural haemorrhage occurs more frequently than intraventricular or subarachnoid haemorrhage. Instrumental and assisted deliveries are associated with an increased incidence of subdural haemorrhage though these rarely cause significant long term damage. Careful autopsy, particularly of the neck and paravertebral tissues, spinal cord, brainstem and nerve roots is important where trauma is suspected. Tearing of nerve roots or fibre bundles in the spinal cord is readily demonstrated under the microscope using immunocytochemistry to beta-amyloid precursor protein. Disorders of the spinal cord, peripheral nerve and muscle as well as some metabolic diseases may cause a baby to be both floppy and weak. Metabolic disease, including peroxisomal disorders, non-ketotic hyperglycinaemia, lipid and glycogen storage disorders and mitochondrial diseases may cause profound hypotonia and respiratory failure at birth or shortly afterwards.

[Clinical course and prognosis in hypoxic-ischemic encephalopathy]

BACKGROUND

Establishing the value of neurological examination, and additional diagnostic methods (ultrasonography and magnetic resonance imaging of the brain) in the diagnosis and prognosis of hypoxic-ischemic encephalopathy and its treatment, tracking the clinical course, and making the prognosis of neurological development in newborn infants with hypoxic-ischemic encephalopathy.

METHODS

The group of 40 term newborn infants with suspected intrauterine asphyxia was examined. All the infants were prospectively followed until the 3rd year of age at the Clinic for Neurology and Psychiatry for Children and Youth in order to estimate their neurological development and to diagnose the occurrence of persistent neurological disorders. All the infants were analyzed by their gestational age and Apgar score in the 1st and the 5th minute of life. They were all examined neurologically and by ultrasonography in the first week of life and, repeatedly, at the age of 1, 3, 6, 9, 12, 18, as well as in the 24th month of life. They were treated by the standard methods for this disease. Finally, all the infants were examined neurologically and by magnetic resonance imaging of the brain in their 3rd year of age. On the basis of neurological finding infants were divided into 3 groups: infants with normal neurological finding, infants with mild neurological symptomatology, and infants with severe neurological disorders.

RESULTS

It was shown that neurological finding, ultrasonography and magnetic resonance imaging of the brain positively correlated with the later neurological development of the infants with hypoxic-ischemic encephalopathy.

CONCLUSION

Only the combined use of these techniques had full diagnostic and prognostic significance, emphasizing that the integrative approach was very important in the diagnosis of brain lesions in infants.

Origin and timing of brain lesions in term infants with neonatal encephalopathy

BACKGROUND

The role of intrapartum asphyxia in neonatal encephalopathy and seizures in term infants is not clear, and antenatal factors are being implicated in the causal pathway for these disorders. However, there is no evidence that brain damage occurs before birth. We aimed to test the hypothesis that neonatal encephalopathy, early neonatal seizures, or both result from early antenatal insults.

METHODS

We used brain MRI or post-mortem examination in 351 fullterm infants with neonatal encephalopathy, early seizures, or both to distinguish between lesions acquired antenatally and those that developed in the intrapartum and early post-partum period. We excluded infants with major congenital malformations or obvious chromosomal disorders. Infants were divided into two groups: those with neonatal encephalopathy (with or without seizures), and evidence of perinatal asphyxia (group 1); and those without other evidence of encephalopathy, but who presented with seizures within 3 days of birth (group 2).

FINDINGS

Brain images showed evidence of an acute insult without established injury or atrophy in 197 (80%) of infants in group 1, MRI showed evidence of established injury in only 2 infants (<1%), although tiny foci of established white matter gliosis, in addition to acute injury, were seen in three of 21 on post-mortem examination. In group 2, acute focal damage was noted in 62 (69%) of infants. Two (3%) also had evidence of antenatal injury.

INTERPRETATION

Although our results cannot exclude the possibility that antenatal or genetic factors might predispose some infants to perinatal brain injury, our data strongly suggest that events in the immediate perinatal period are most important in neonatal brain injury.